Linnaeus was born in the countryside of Småland, in southern Sweden. Linnaeus received most of his higher education at Uppsala University, and began giving lectures in botany there in 1730. He lived abroad between 1735 and 1738, where he studied and also published a first edition of his Systema Naturae in the Netherlands. He then returned to Sweden, where he became professor of botany at Uppsala. In the 1740s, he was sent on several journeys through Sweden to find and classify plants and animals. In the 1750s and 60s, he continued to collect and classify animals, plants, and minerals, and published several volumes. At the time of his death, he was one of the most acclaimed scientists in Europe.

The Swiss philosopher Jean-Jacques Rousseau sent him the message: "Tell him I know no greater man on earth."[2] The German writer Johann Wolfgang von Goethe wrote: "With the exception of Shakespeare and Spinoza, I know no one among the no longer living who has influenced me more strongly."[2] Swedish author August Strindberg wrote: "Linnaeus was in reality a poet who happened to become a naturalist".[3] Among other compliments, Linnaeus has been calledPrinceps botanicorum (Prince of Botanists), "The Pliny of the North," and "The Second Adam".[4]

ChildhoodBirth place of Linnaeus at Råshult.Carl Linnaeus was born in the village of Råshult in Småland, Sweden on 23 May 1707. He was the first child of Nils Ingemarsson Linnaeus and Christina Brodersonia. His father was the first in his ancestry to adopt a permanent surname. Before that, ancestors had used the patronymic naming system of Scandinavian countries: his father was named Ingemarsson after his father Ingemar Bengtsson. When Nils was admitted to the University of Lund, he had to take on a family name. He adopted the Latinate name Linnæus after a giant linden tree (or lime tree), lind in Swedish, that grew on the family homestead.[7] This name was spelled with the æligature. When Carl was born, he was named Carl Linnæus, with his father's family name. The son also always spelled it with the æ ligature, both in handwritten documents and in publications.[8]Carl's patronymic would have been Nilsson, as in Carl Nilsson Linnæus.

One of a long line of peasants and priests, Nils was an amateur botanist, a Lutheranminister, and the curate of the small village of Stenbrohult in Småland. Christina was the daughter of the rector of Stenbrohult, Samuel Brodersonius. She subsequently gave birth to three daughters and another son, Samuel (who would eventually succeed their father as rector of Stenbrohult and write a manual on beekeeping).[7][9][10] A year after Linnaeus' birth, his grandfather Samuel Brodersonius died, and his father Nils became the rector of Stenbrohult. The family moved into the rectory from the curate's house.[8][11]

Even in his early years, Linnaeus seemed to have a liking for plants, flowers in particular. Whenever he was upset, he was given a flower, which immediately calmed him. Nils spent much time in his garden and often showed flowers to Linnaeus and told him their names. Soon Linnaeus was given his own patch of earth where he could grow plants.[12]

Early educationHis father began teaching Linnaeus Latin, religion, and geography at an early age; one account says that due to family use of Latin for conversation, the boy learned Latin before he learned Swedish. When Linnaeus was seven, Nils decided to hire a tutor for him. The parents picked Johan Telander, a son of a local yeoman. Linnaeus did not like him, writing in his autobiography that Telander "was better calculated to extinguish a child's talents than develop them."[13] Two years after his tutoring had begun, he was sent to the Lower Grammar School at Växjö in 1717.[14] Linnaeus rarely studied, often going to the countryside to look for plants. He reached the last year of the Lower School when he was fifteen, which was taught by the headmaster, Daniel Lannerus, who was interested in botany. Lannerus noticed Linnaeus' interest in botany and gave him the run of his garden. He also introduced him to Johan Rothman, the state doctor of Småland and a teacher at Växjö Gymnasium. Also a botanist, Rothman broadened Linnaeus' interest in botany and helped him develop an interest in medicine.[15][16]

Linnaeus entered the Växjö Gymnasium in 1724, where he studied mainly Greek, Hebrew, theology and mathematics, a curriculum designed for boys preparing for the priesthood.[17][18] In the last year at the gymnasium, Linnaeus' father visited to ask the professors how his son's studies were progressing; to his dismay, most said that the boy would never become a scholar. Rothman believed otherwise, suggesting Linnaeus could have a future in medicine. The doctor offered to have Linnaeus live with his family in Växjö and to teach him physiology and botany. Nils accepted this offer.[19][20]

The local doctor Kilian Stobaeus offered Linnaeus tutoring and lodging, as well as the use of his library, which included many books about botany. He also gave the student free admission to his lectures.[23][24] In his spare time, Linnaeus explored the flora of Skåne, together with students sharing the same interests.[25]

UppsalaIn August 1728, Linnaeus decided to attend Uppsala University on the advice of Rothman, who believed it would be a better choice if Linnaeus wanted to study both medicine and botany. Rothman based this recommendation on the two professors who taught at the medical faculty at Uppsala: Olof Rudbeck the Younger and Lars Roberg. Although Rudbeck and Roberg had undoubtedly been good professors, by then they were older and not so interested in teaching. Rudbeck no longer gave public lectures, and had others stand in for him. The botany, zoology, pharmacology and anatomy lectures were not in their best state.[26] In Uppsala, Linnaeus met a new benefactor, Olof Celsius, who was a professor of theology and an amateur botanist.[27] He received Linnaeus into his home and allowed him use of his library, which was one of the richest botanical libraries in Sweden.[28]

In 1729, Linnaeus wrote a thesis, Praeludia Sponsaliorum Plantarum on plant sexuality. This attracted the attention of Rudbeck; in May 1730, he selected Linnaeus to give lectures at the University although the young man was only a second-year student. His lectures were popular, and Linnaeus often addressed an audience of 300 people.[29] In June, Linnaeus moved from Celsius' house to Rudbeck's to become the tutor of the three youngest of his 24 children. His friendship with Celsius did not wane and they continued their botanical expeditions.[30] Over that winter, Linnaeus began to doubt Tournefort's system of classification and decided to create one of his own. His plan was to divide the plants by the number of stamens and pistils. He began writing several books, which would later result in, for example, Genera Plantarum and Critica Botanica. He also produced a book on the plants grown in the Uppsala Botanical Garden, Adonis Uplandicus.[31]

Rudbeck's former assistant, Nils Rosén, returned to the University in March 1731 with a degree in medicine. Rosén started giving anatomy lectures and tried to take over Linnaeus' botany lectures, but Rudbeck prevented that. Until December, Rosén gave Linnaeus private tutoring in medicine. In December, Linnaeus had a "disagreement" with Rudbeck's wife and had to move out of his mentor's house; his relationship with Rudbeck did not appear to suffer. That Christmas, Linnaeus returned home to Stenbrohult to visit his parents for the first time in about three years. His mother had disapproved of his failing to become a priest, but she was pleased to learn he was teaching at the University.[31][32]

Linnaeus began his expedition from Uppsala in May; he travelled on foot and horse, bringing with him his journal, botanical and ornithological manuscripts and sheets of paper for pressing plants. Near Gävle he found great quantities of Campanula serpyllifolia, later known as Linnaea borealis, the twinflower that would become his favourite.[35] He sometimes dismounted on the way to examine a flower or rock[36] and was particularly interested in mosses and lichens, the latter a main part of the diet of the reindeer, a common animal in Lapland.[37]

Linnaeus travelled clockwise around the coast of the Gulf of Bothnia, making major inland incursions from Umeå, Luleå and Tornio. He returned from his six-month long, over 2,000 kilometres (1,200 mi) expedition in October, having gathered and observed many plants, birds and rocks.[38][39][40] Although Lapland was a region with limitedbiodiversity, Linnaeus described about 100 previously unidentified plants. These became the basis of his book Flora Lapponica.[41][42]

In Flora Lapponica Linnaeus' ideas about nomenclature and classification were first used in a practical way, making this the first proto-modern Flora.[43] The account covered 534 species, used the Linnaean classification system and included, for the described species, geographical distribution and taxonomic notes. It was Augustin Pyramus de Candolle who attributed Linnaeus with Flora Lapponica as the first example in the botanical genre of Flora writing. Botanical historian E.L. Greene describedFlora Lapponica as "the most classic and delightful of Linnaeus’s writings".

It was also during this expedition that Linnaeus had a flash of insight regarding the classification of mammals. Upon observing the lower jawbone of a horse at the side of a road he was traveling, Linnaeus remarked: "If I only knew how many teeth and of what kind every animal had, how many teats and where they were placed, I should perhaps be able to work out a perfectly natural system for the arrangement of all quadrupeds."[44]

DalarnaIn 1734, Linnaeus led a small group of students to Dalarna. Funded by the Governor of Dalarna, the expedition was to catalogue known natural resources and discover new ones, but also to gather intelligence on Norwegian mining activities at Røros.[40]

In April 1735, Linnaeus and Sohlberg set out for the Netherlands, with Linnaeus to take a doctoral degree in medicine at the University of Harderwijk.[47] On the way, they stopped in Hamburg, where they met the mayor, who proudly showed them a wonder of nature which he possessed: the taxidermied remains of a seven-headed hydra. Linnaeus quickly discovered it was a fake: jaws and clawed feet from weasels and skins from snakes had been glued together. The provenance of the hydra suggested to Linnaeus it had been manufactured by monks to represent the Beast of Revelation. As much as this may have upset the mayor, Linnaeus made his observations public and the mayor's dreams of selling the hydra for an enormous sum were ruined. Fearing his wrath, Linnaeus and Sohlberg had to leave Hamburg quickly.[48][49]

When Linnaeus reached Harderwijk, he began taking his degree immediately. First he handed in a thesis on the cause of malaria he had written in Sweden, which he then defended in a public debate. The next step was to take an oral examination and to diagnose a patient. After less than two weeks, he took his degree and became a doctor, at the age of 28.[48][50] During the summer, Linnaeus met a friend from Uppsala, Peter Artedi. Before their departure from Uppsala, Artedi and Linnaeus had decided should one of them die, the survivor would finish the other's work. Ten weeks later, Artedi drowned in one of the canals of Amsterdam, and his unfinished manuscript on the classification of fish was left to Linnaeus to complete.[51][52]

Publishing of Systema NaturaeOne of the first scientists Linnaeus met in the Netherlands was Johan Frederik Gronovius to whom Linnaeus showed one of the several manuscripts he had brought with him from Sweden. The manuscript described a new system for classifying plants. When Gronovius saw it, he was very impressed, and offered to help pay for the printing. With an additional monetary contribution by the Scottish doctor Isaac Lawson, the manuscript was published as Systema Naturae.[53][54]

Linnaeus became acquainted with one of the most respected physicians and botanists in the Netherlands, Herman Boerhaave, who tried to convince Linnaeus to make a career there. Boerhaave offered him a journey to South Africa and America, but Linnaeus declined, stating he would not stand the heat. Instead, Boerhaave convinced Linnaeus that he should visit the botanist Johannes Burman. After his visit, Burman, impressed with his guest's knowledge, decided Linnaeus should stay with him during the winter. During his stay, Linnaeus helped Burman with his Thesaurus Zeylanicus. Burman also helped Linnaeus with the books on which he was working: Fundamenta Botanica and Bibliotheca Botanica.[55]

In July 1736, Linnaeus travelled to England, at Clifford's expense.[58] He went to London to visit Sir Hans Sloane, a collector of natural history, and to see his cabinet,[59]as well as to visit the Chelsea Physic Garden and its keeper, Philip Miller. He taught Miller about his new system of subdividing plants, as described in Systema Naturae. Miller was impressed, and from then on started to arrange the garden according to Linnaeus' system.[60] Linnaeus also traveled to Oxford University to visit the botanistJohann Jacob Dillenius. He failed, however, to make Dillenius publicly accept his new classification system. He then returned to Hartecamp, bringing with him many specimens of rare plants.[61] The next year, he published Genera Plantarum, in which he described 935 genera of plants, and shortly thereafter he supplemented it withCorollarium Generum Plantarum, with another sixty (sexaginta) genera.[62]

His work at Hartecamp led to another book, Hortus Cliffortianus, a catalogue of the botanical holdings in the herbarium and botanical garden of Hartecamp. He wrote it in nine months (completed in July 1737), but it was not published until 1738.[55] It contains the first use of the name Nepenthes, which Linnaeus used to describe a genus of pitcher plants.[63][note 2]

Linnaeus stayed with Clifford at Hartecamp until 18 October 1737 (new style), when he left the house to return to Sweden. Illness and the kindness of Dutch friends obliged him to stay some months longer in Holland. In May 1738, he set out for Sweden again. On the way home, he stayed in Paris for about a month, visiting botanists such as Antoine de Jussieu. After his return, Linnaeus never left Sweden again.[64][65]

Because his finances had improved and were now sufficient to support a family, he received permission to marry his fiancée, Sara Elisabeth Moræa. Their wedding was held 26 June 1739. Seven months later, Sara gave birth to their first son, Carl. Two years later, a daughter, Elisabeth Christina, was born, and the subsequent year Sara gave birth to Sara Magdalena, who died 15 days old. Sara and Linnaeus would later have four other children: Lovisa, Sara Christina, Johannes and Sophia.[66][71]

In May 1741, Linnaeus was appointed Professor of Medicine at Uppsala University, first with the responsibility of the medicine-related matters. Soon, he changed place with the other Professor of Medicine, Nils Rosén, and thus was responsible for the Botanical Garden (which he would thoroughly reconstruct and expand), botany andnatural history, instead. In October that same year, his wife and nine-year-old son followed him to live in Uppsala.[72]

Further exploration of SwedenÖland and GotlandTen days after he was appointed Professor, he undertook an expedition to the island provinces of Öland and Gotland with six students from the university, to look for plants useful in medicine. First, they travelled to Öland and stayed there until 21 June, when they sailed to Visby in Gotland. Linnaeus and the students stayed on Gotland for about a month, and then returned to Uppsala. During this expedition, they found 100 previously unrecorded plants. The observations from the expedition were later published in Öländska och Gothländska Resa, written in Swedish. Like Flora Lapponica, it contained both zoological and botanical observations, as well as observations concerning the culture in Öland and Gotland.[73][74]

During the summer of 1745, Linnaeus published two more books: Flora Suecica and Fauna Suecica. Flora Suecica was a strictly botanical book, while Fauna Suecicawas zoological.[66][75]Anders Celsius had created the temperature scale named after him in 1742. Celsius' scale was inverted compared to today, the boiling point at 0°C and freezing point at 100°C. In 1745, Linnaeus inverted the scale to its present standard.[76]

VästergötlandIn the summer of 1746, Linnaeus was once again commissioned by the Government to carry out an expedition, this time to the Swedish province of Västergötland. He set out from Uppsala on 12 June and returned on 11 August. On the expedition his primary companion was Erik Gustaf Lidbeck, a student who had accompanied him on his previous journey. Linnaeus described his findings from the expedition in the book Wästgöta-Resa, published the next year.[73][77] After returning from the journey the Government decided Linnaeus should take on another expedition to the southernmost province Scania. This journey was postponed, as Linnaeus felt too busy.[66]

ScaniaIn the spring of 1749, Linnaeus could finally journey to Scania, again commissioned by the Government. With him he brought his student, Olof Söderberg. On the way to Scania, he made his last visit to his brothers and sisters in Stenbrohult since his father had died the previous year. The expedition was similar to the previous journeys in most aspects, but this time he was also ordered to find the best place to grow walnut andSwedish whitebeam trees; these trees were used by the military to make rifles. The journey was successful, and Linnaeus' observations were published the next year in Skånska Resa.[80][81]

Publishing of Philosophia BotanicaLinnaeus published Philosophia Botanica in 1751. The book contained a complete survey of the taxonomy system he had been using in his earlier works. It also contained information of how to keep a journal on travels and how to maintain a botanical garden.[84]

Publishing of Species PlantarumLinnaeus published Species Plantarum, the work which is now internationally accepted as the starting point of modern botanical nomenclature, in 1753. The first volume was issued on May 24, the second volume followed on August 16[85] of the same year.[86][87] The book contained 1,200 pages and was published in two volumes; it described over 7,300 species.[88][89] The same year the king dubbed him knight of the Order of the Polar Star, the first civilian in Sweden to become a knight in this order. He was then seldom seen not wearing the order.[90]

EnnoblementLinnaeus felt Uppsala was too noisy and unhealthy, so he bought two farms in 1758: Hammarby and Sävja. The next year, he bought a neighbouring farm, Edeby. He spent the summers with his family at Hammarby; initially it only had a small one-storey house, but in 1762 a new, larger main building was added.[81][91] In Hammarby, Linnaeus made a garden where he could grow plants that could not be grown in the Botanical Garden in Uppsala. He began constructing a museum on a hill behind Hammarby in 1766, where he moved his library and collection of plants. A fire that destroyed about one third of Uppsala and had threatened his residence there necessitated the move.[92]

Since the initial release of Systema Naturae in 1735, the book had been expanded and reprinted several times; the tenth edition was released in 1758. This edition established itself as the starting point forzoological nomenclature, the equivalent of Species Plantarum.[88][93]

The Swedish king Adolf Frederick granted Linnaeus nobility in 1757, but he was not ennobled until 1761. With his ennoblement, he took the name Carl von Linné (Latinized as Carolus a Linné), 'Linné' being a shortened and gallicised version of 'Linnæus', and the German title 'von' signifying his ennoblement.[1] The noble family's coat of arms prominently features a twinflower, one of Linnaeus' favourite plants; it was given the scientific name Linnaea borealis in his honour by Gronovius. The shield in the coat of arms is divided into thirds: red, black and green for the three kingdoms of nature (animal, mineral and vegetable) in Linnaean classification; in the center is an egg "to denote Nature, which is continued and perpetuated in ovo." At the bottom is a phrase in Latin, borrowed from the Aeneid, which reads "FAMAM EXTENDERE FACTIS": We extend our fame by our deeds.[94][95][96]

Last yearsHeadstone of Carl Linnaeus and his sonCarolus Linnaeus the Younger.Linnaeus was relieved of his duties in the Royal Swedish Academy of Science in 1763, but continued his work there as usual for more than ten years after.[66] He stepped down as rector at Uppsala University in December 1772, mostly due to his declining health.[65][97]

Linnaeus' last years were troubled by illness. He had suffered from a disease called the Uppsala fever in 1764, but survived thanks to the care of Rosén. He developedsciatica in 1773, and the next year, he had a stroke which partially paralysed him.[98] He suffered a second stroke in 1776, losing the use of his right side and leaving him bereft of his memory; while still able to admire his own writings, he could not recognize himself as their author.[99][100]

In December 1777, he had another stroke which greatly weakened him, and eventually led to his death on 10 January 1778 in Hammarby.[97][101] Despite his desire to be buried in Hammarby, he was interred in Uppsala Cathedral on 22 January.[102][103]

His library and collections were left to his widow Sara and their children. Joseph Banks, an English botanist, wanted to buy the collection, but his son Carl refused and moved the collection to Uppsala. However, in 1783 Carl died and Sara inherited the collection, having outlived both her husband and son. She tried to sell it to Banks, but he was no longer interested; instead an acquaintance of his agreed to buy the collection. The acquaintance was a 24 year old medical student, James Edward Smith, who bought the whole collection: 14,000 plants, 3,198 insects, 1,564 shells, about 3,000 letters and 1,600 books. Smith founded the Linnean Society of London five years later.[103][104]

ApostlesMain article: Apostles of LinnaeusPehr Forsskål was among the apostles who met a tragic fate abroad.Apostle Daniel Solander (far left) withJoseph Banks (left, sitting) accompaniedJames Cook (center) on his journey to Australia.During Linnaeus' time as Professor and Rector of Uppsala University, he taught many devoted students, 17 of whom he called "apostles". They were the most promising, most committed students, and all of them made botanical expeditions to various places in the world, often with his help. The amount of this help varied; sometimes he used his influence as Rector to grant his apostles a scholarship or a place on an expedition.[105] To most of the apostles he gave instructions of what to look for on their journeys. Abroad, the apostles collected and organised new plants, animals and minerals according to Linnaeus' system. Most of them also gave some of their collection to Linnaeus when their journey was finished.[106] Thanks to these students, the Linnaean system of taxonomy spread through the world without Linnaeus ever having to travel outside Sweden after his return from Holland.[107] The British botanist William T. Stearn notes without Linnaeus' new system, it would not have been possible for the apostles to collect and organise so many new specimens.[108] Many of the apostles died during their expeditions.

Early expeditionsChristopher Tärnström, the first apostle and a 43-year-old pastor with a wife and children, made his journey in 1746. He boarded a Swedish East India Company ship headed for China. Tärnström never reached his destination, dying of a tropical fever on Côn Sơn Island the same year. Tärnström's widow blamed Linnaeus for making her children fatherless, causing Linnaeus to prefer sending out younger, unmarried students after Tärnström.[109] Six other apostles later died on their expeditions, includingPehr Forsskål and Pehr Löfling.[108]

Two years after Tärnström's expedition, Finnish-born Pehr Kalm set out as the second apostle to North America. There he spent two-and-a-half years studying the flora and fauna of Pennsylvania, New York, New Jersey and Canada. Linnaeus was overjoyed when Kalm returned, bringing back with him many pressed flowers and seeds. At least 90 of the 700 North American species described in Species Plantarum had been brought back by Kalm.[110]

Cook expeditions and JapanDaniel Solander was living in Linnaeus' house during his time as a student in Uppsala. Linnaeus was very fond of him, promising Solander his oldest daughter's hand in marriage. On Linnaeus' recommendation, Solander travelled to England in 1760, where he met the English botanist Joseph Banks. With Banks, Solander joined James Cook on his expedition to Oceania on the Endeavour in 1768–71.[111][112] Solander was not the only apostle to journey with James Cook; Anders Sparrman followed on the Resolution in 1772–75 bound for, among other places, Oceania and South America. Sparrman made many other expeditions, one of them to South Africa.[113]

Perhaps the most famous and successful apostle was Carl Peter Thunberg, who embarked on a nine-year expedition in 1770. He stayed in South Africa for three years, then travelled to Japan. All foreigners in Japan were forced to stay on the island of Dejima outside Nagasaki, so it was thus hard for Thunberg to study the flora. He did, however, manage to persuade some of the translators to bring him different plants, and he also found plants in the gardens of Dejima. He returned to Sweden in 1779, one year after Linnaeus' death.[114]

Major publicationsMain article: Carl Linnaeus bibliographySystema NaturaeTitle page of the 10th edition of Systema Naturæ (1758).Main articles: Systema Naturae and 10th edition of Systema NaturaeThe first edition of Systema Naturae was printed in the Netherlands in 1735. It was a twelve-page work.[115] By the time it reached its 10th edition in 1758, it classified 4,400 species of animals and 7,700 species of plants. In it, the unwieldy names mostly used at the time, such as "Physalis annua ramosissima, ramis angulosis glabris, foliis dentato-serratis", were supplemented with concise and now familiar "binomials", composed of the generic name, followed by a specific epithet – in the case given,Physalis angulata. These binomials could serve as a label to refer to the species. Higher taxa were constructed and arranged in a simple and orderly manner. Although the system, now known as binomial nomenclature, was partially developed by the Bauhin brothers (see Gaspard Bauhin and Johann Bauhin) almost 200 years earlier,[citation needed] Linnaeus was the first to use it consistently throughout the work, including in monospecific genera, and may be said to have popularised it within the scientific community. Linnaeus named taxa in ways that struck him as common-sensical; for example, human beings are Homo sapiens (see sapience). The group "Mammalia" was named for their mammary glands because one of the defining characteristics of mammals is they nurse their young.

Species PlantarumMain article: Species PlantarumSpecies Plantarum (or, more fully, Species Plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas) was first published in 1753, as a two-volume work. Its prime importance is perhaps that it is the primary starting point of plant nomenclature as it exists today.

In 1754, Linnaeus divided the plant Kingdom into 25 classes. One, Cryptogamia, included all the plants with concealed reproductive parts (algae, fungi, mosses and liverworts and ferns).[116]

Systema PlantarumSystema Plantarum, published posthumously in 1779, integrated the botanical aspects of Systema Naturae with Species Plantarum (and, de facto, Genera Plantarum) to make a complete work. This work actually presented the fourth edition of Species Plantarum. A follow-up titled Supplementum Plantarum was published by Carolus Linnaeus the Younger in 1782.

The Linnaean system classified nature within a nested hierarchy, starting with three kingdoms. Kingdoms were divided into Classes and they, in turn, into Orders, which were divided into Genera (singular: genus), which were divided into Species (singular: species). Below the rank of species he sometimes recognized taxa of a lower (unnamed) rank; these have since acquired standardised names such as variety in botany and subspecies in zoology.

Linnaeus' groupings were based upon shared physical characteristics. Only his groupings for animals survive, and the groupings themselves have been significantly changed since their conception, as have the principles behind them. Nevertheless, Linnaeus is credited with establishing the idea of a hierarchical structure of classification which is based upon observable characteristics. While the underlying details concerning what are considered to be scientifically valid "observable characteristics" have changed with expanding knowledge (for example, DNA sequencing, unavailable in Linnaeus' time, has proven to be a tool of considerable utility for classifying living organisms and establishing their evolutionary relationships), the fundamental principle remains sound.

Views on mankindAccording to German biologist Ernst Haeckel, the question of man's origin began with Linnaeus. He helped future research in the natural history of man by describing humans just as he described any other plant or animal.[118] He was the first person to place humans in a system of biological classification.

It does not please [you] that I've placed Man among the Anthropomorpha, perhaps because of the term 'with human form'[note 4], but man learns to know himself. Let's not quibble over words. It will be the same to me whatever name we apply. But I seek from you and from the whole world a generic difference between man and simian that [follows] from the principles of Natural History.[note 5] I absolutely know of none. If only someone might tell me a single one! If I would have called man a simian or vice versa, I would have brought together all the theologians against me. Perhaps I ought to have by virtue of the law of the discipline.

The theological concerns were twofold: first, putting man at the same level as monkeys or apes would lower the spiritually higher position that man was assumed to have in the great chain of being, and second, because the Bible says man was created in the image of God[123] (theomorphism), if monkeys/apes and humans were not distinctly and separately designed, that would mean monkeys and apes were created in the image of God as well. This was something many could not accept.[124] The conflict between worldviews based on science and theology that was caused by asserting man was a type of animal would simmer for a century until the much greater, and still ongoing, creation–evolution controversy began in earnest with the publication of On the Origin of Species by Charles Darwin in 1859.

After such criticism, Linnaeus felt he needed to explain himself more clearly. The 10th edition of Systema Naturae introduced new terms, including Mammalia and Primates, the latter of which would replaceAnthropomorpha[125] as well as giving humans the full binomial Homo sapiens.[126] The new classification received less criticism, but many natural historians still believed he had demoted humans from their former place to rule over nature, not be a part of it. Linnaeus believed that man biologically belongs to the animal kingdom and had to be included in it.[127] In his book Dieta Naturalis, he said, "One should not vent one's wrath on animals, Theology decree that man has a soul and that the animals are mere 'aoutomata mechanica,' but I believe they would be better advised that animals have a soul and that the difference is of nobility."[128]

In early editions of Systema Naturae, many well-known legendary creatures were included such as the phoenix, dragon and manticore as well as cryptids like thesatyrus,[133] which Linnaeus collected into the catch-all category Paradoxa. Broberg thought Linnaeus was trying to offer a natural explanation and demystify the world of superstition.[134] Linnaeus tried to debunk some of these creatures, as he had with the hydra; regarding the purported remains of dragons, Linnaeus wrote that they were either derived from lizards or rays.[135] For Homo troglodytes he asked the Swedish East India Company to search for one, but they did not find any signs of its existence.[136]Homo lar has since been reclassified as Hylobates lar, the lar gibbon.

^ ab Carl Linnaeus was born in 1707 on 13 May (Swedish Style) or 23 May according to the modern calendar. According to the Julian calendar he was born 12 May. (Blunt 2004, p. 12)

^ "If this is not Helen's Nepenthes, it certainly will be for all botanists. What botanist would not be filled with admiration if, after a long journey, he should find this wonderful plant. In his astonishment past ills would be forgotten when beholding this admirable work of the Creator!" (translated from Latin by Harry Veitch)

^Frängsmyr et al. (1983). p. 167. quotes Linnaeus explaining the real difference would necessarily be absent from his classification system, as it was not a morphological characteristic: "I well know what a splendidly great difference there is [between] a man and a bestia [literally, "beast"; that is, a non-human animal] when I look at them from a point of view of morality. Man is the animal which the Creator has seen fit to honor with such a magnificent mind and has condescended to adopt as his favorite and for which he has prepared a nobler life". See also [1] in which Linnaeus cites the significant capacity to reason as the distinguishing characteristic of humans.

^ Others who followed were more inclined to give humans a special place in classification; Johann Friedrich Blumenbach in the first edition of his Manual of Natural History (1779), proposed that the primates be divided into the Quadrumana (four-handed, i.e. apes and monkeys) and Bimana (two-handed, i.e. humans). This distinction was taken up by other naturalists, most notably Georges Cuvier. Some elevated the distinction to the level of order. However, the many affinities between humans and other primates — and especially the great apes — made it clear that the distinction made no scientific sense. Charles Darwin wrote, in The Descent of Man in 1871:The greater number of naturalists who have taken into consideration the whole structure of man, including his mental faculties, have followed Blumenbach and Cuvier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the orders of the Quadrumana, Carnivora, etc. Recently many of our best naturalists have recurred to the view first propounded by Linnaeus, so remarkable for his sagacity, and have placed man in the same Order with the Quadrumana, under the title of the Primates. The justice of this conclusion will be admitted: for in the first place, we must bear in mind the comparative insignificance for classification of the great development of the brain in man, and that the strongly marked differences between the skulls of man and the Quadrumana (lately insisted upon by Bischoff, Aeby, and others) apparently follow from their differently developed brains. In the second place, we must remember that nearly all the other and more important differences between man and the Quadrumana are manifestly adaptive in their nature, and relate chiefly to the erect position of man; such as the structure of his hand, foot, and pelvis, the curvature of his spine, and the position of his head.